Method for producing synthetic rubberlike polymers



Dec. 23, 1947. w. J. SPARKS ETAL 2,433,070 METHOD FOR PRODUCINGSYNTHETIC RUBBERLIKE POLYMERS v 5 Sheets-Sheet 1 FIG. ---1 'FIGII FIG-2FTEWN 5 Sheets-Sheet 2 w. J. SPARKS ETAL v Filed Jan. 1, 1943 METHOD FORPRODUCING SYNTHETIC RUBBERLIKE POLYMERS Dec. 23, 19.47.

JVKS/MQW Dec. 23, 1947; w.,J. SPARKS ETAL 2,433,0

METHOD FOR PRODUCING SYNTHETIC RUBBERL IKE POLYHERS 5 Shee'c'sShe et 4Filed Jan. 1, 1943 illl-Illl. I

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Patented Dec. 23, 1947 umreo sTA'res PATENT OFFICE METHOD FOR PRODUCINGSYNTHETIC RUBBERLIKE POLYMERS William Sparks and buta'dienes up to about12 carbon atoms per molecule, by a process utilizing a Friedel-Craftstype catalyst such as aluminum chloride dissolved in a low freezing,non-complex forming solvent, such as a lower alkyl halide having lessthan about carbon atoms, or carbon disulfide or the like. This reactionon a commercial scale has previously been conducted by the use of liquidethylene as a refrigerant mixed with the olefins, the reaction beingconducted in a closed reactor provided with a refrigerant jacket filledwith liquid ethylene, elaborate precautions being taken torecovervolatilized components for purification and reuse, since all are ratherexpensive mate rials. This process involves a great deal of machinery,much of which must be made of special steels to withstand the lowtemperatures involved and the apparatus is expensive to build andinstall and complicated to operate.

The present invention utilizes a mixture 0 polymerizable olefinicmaterial with a volatile refrigerant under such circumstances that theheat of' polymerization of the olefinic material volatilizes asufiicient amount of the volatile refrigerant in such intimate contactwith the solid polymer that the gas is occluded in the solid polymer insufilcient quantity to reduce its a John D. Cali'ee, Cranford, N. J.,assignors to Standard Oil Development Company, a corporation of DelawareApplication January 1, 1943, Serial No. 47 0,958 2 Claims. (Cl. 260-93)2 the occlusion of volatilized refrigerant in the solid polymer whichcauses it to float upon the surface of the body of cold olefinic mixturein the tank. This surface may, without harm, be exposed to theatmosphere, since, when solid carbon dioxide is used, the vapor pressureof the olefinic material is so low that very little loss occurs andpractically the only volatilizate is carbon dioxide which isnon-poisonous and noncombustible. The floating solid polymer with itsoccluded gaseous refrigerant is then conveniently skimmed off from thesurface and further processed.

The apparatus may further utilize a rapid circulation of water intowhich the polymer skimmed from the surface of the reactant material isthrown for purification, transportation,

and further treatment.

The process of the invention preferably utilizes a mixture of anisoolefin and a diolefin, preferably isobutylene, with isoprene orpiperylene or dimethyl butadiene saturated with dissolved cardensitysubstantially below the density of the.

cold polymerization mixture, thereby causing the solid polymer to floatupon the surface in a location in which, it is conveniently availablefor removal by a strainer in the hands of an attending workman.

This process of the invention may conveniently be practised in a simplewooden tank having circulating means for keeping the contents in motionand a shallow portion over which a rapid now of olefinic mixture occurs,onto which the catalyst may be applied. The application of the catalystcauses a prompt polymerization reaction,

and the application a suchna point permits of,

bon dioxide and cooled with pulverized solid carbon dioxide (dry ice'f)A supply of the cold mixed olefinic material is delivered to the woodenreactor, and a small stream of catalyst is applied to thecirculating-mixture. The resulting polymer is strained out and collectedby a workman equipped with a strainer ladle, the excess reactantmaterial being drained oil and the solid polymer thrown immediately intoa rapid circulating stream of warm water in'whichthe catalyst isdestroyed, the small excess of reactants volatilized out and thematerial washed, ready for drying, milling and further processing.

Thus, the device of the invention provides a polymerization reactorsuitable for operation by unskilled mechanics with a minimum waste ofvaluable raw materials and a minimum cost of installation; the processutilizes a simple olefinic polymerization procedure with a dissolvedFriedel-Crafts catalyst to produce the polymerization, while the gaseousrefrigerant volatilized by the heat of reaction of the polymerizationpuffsv up the solid polymer into a body which floats upon the surface ofthe cold reaction mixture. The polymer can be removed from the reactionmixture by a simple strainer to permit recirculation of unreactedolefinic material through a body of solid carbon dioxide for recoolingand return, together with additional olefinic material, to thepolymerization zone for further polymerization. Other objects anddetails of the process and products of the invention w ll be apparentfrom the following descriplating pump member if so that a tion when readin connection with the accompanying drawings in which Fig. 1' is a sideview of a wooden polymerization reactoraccording to the invention;

Fig. 2 represents a longitudinal vertical section of the same reactor;

Fig. 3 is a top view of the reactor:

' with the catalyst solutionprepared in the tank Fig. 4 is a transversevertical section of the I reactor;

Fig. 5 is a top view of a set of reactors together with the circulatingwater stream for quenching;

Fig. 6 is an end elevation of the polymerization equipment;

Fig. '7 is a side view of the embodiment partaking of the character of aflow sheet and Fig. 8 is a side view in vertical section of analternative embodiment of the polymerizer.

Referring to the drawing, the polymerizer itself consists of a woodentank member I within which there is positioned a partition member 2 nearone end of the tank, extending across the width oi the tank but with anopen space below the lower edge of the partition. Near the middle of thetank there is provided a barrier member 3 extending from the bottom ofthe tank nearly to the top. Along one side of the tank a duct memher 4is provided connected to a propeller well 5 formed between the end ofthe tank and the partition 2 by an auxiliary partition 6; Within thepropeller well 5 there is positioned a propeller member l mounted upon ashaft 8 driven by a convenient source of power 9, an electric motorbeing indicated in the drawing.

Over the barrier 3 there is positioned a supply pipe H equipped with aseries of spray heads as shown and connected to a source of catalystsolution as shown at 53 at the lower right hand portion of Fig. 7. Y

A supply of cold olefinic material is delivered to the reactor throughthe supphr pipe I! and a suDPLv of solid carbon dioxide is placed in thereactor between the partition 2 and the barrier 3.

A number of reactors of the type shown in Fig. 1 are placed side by sideas shown inFig. 5 to cooperate with a single water channel IS. The

reactors are designated A. B, C, D and 'E in Fig. 5.

This water channel i5 conveniently consists of a wooden trough coveredover most of its length, but with openings [6 adjacent to the ends ofthe several polymerizer reactors i. The circulation of water in thistrough is maintained by a circurapid flow of water is maintained pastthe ends of the several water flows through a screen intake to a pipe 2!pump H.

member I! to an leading to the circulating tion. 'Ihe-chhriiedimlv 32.From the cooler 43 the catalyst is delivered to a storage tank 45 whichis kept cool by solid carbon dioxide in a tank 46. From the storage tank45 a pipe 41 leads to a working tank 48, also kept cold by a supply ofdry ice contained in a box 49. The catalyst solution is delivered fromthe tank 48 through a pipe ii and another auxiliary cooler 52 through apipe 53 to the pipe ll over the barrier 3 in the polymerlzer l in Fig.1.

The isobutylene for the polymerizable mixture is delivered through apipe St to a. tank 62 which likewise is equipped with a relief line 63and a cooling coil 64 closely similar to the coolin coil 33. Theisobutylene is delivered at approximately atmospheric temperature andpressure to the pipe line GI and is condensed in the tank 62 by thepresence of a refrigerant in the coil 64 preparatory to the preparationof the polymerization mixture. Simultaneously, the polyolefin,preferably isoprene. is delivered through a pipe line H to a smallertank member '12 also equipped with a relief line l3 and cooling coil 14.The liquid isobutylene, preferably cooled to approximately -78 C., isdelivered through a pipe line to a tank member 82. Simultaneously, thecooled polyoleiln is delivered through a pipe line 15 to the tank 82 andthe oleflns are mixed in the tank 82 by the stirring action of a stirrer83 mounted on a shaft 85 driven by a convenient source of power 85a. Themixed oleflns are delivered through a cooler and a pipe line 81 to eachdelivery pipe I 2 (shown in Figs. 1,2 and 3) in the respective reactorsI.

In the operation of this embodiment of the invention the supply ofisobutylene, preferably of a purity of at least 96%, is delivered fromthe cracking Plant to the pipev line 6|, preferably through a precooler(not shown) so that it is delivered to the tank 62 either in liquid formor at a temperature close to its liquefaction temperature. In the tank62 the isobutylene is cooled tank 82, mixed therein and sent through theI In preparing this mixture it is preferable that it consist of a majorproportion of an isoolefin having from 4 to 'i' when atoms, inclusive,preferably isobutylene and a minor proportion of the polyolefin havingfrom 4 to 12 or 14 carbon atoms per molecule when isobutylene is used,the mixture preferably consists of from Z0 to 99.5 parts of isobutylenewith-from 30 to 0.5 parts of the diclefln. Simultaneously. theFriaiel-Crafts cati w bydelivering the solvent throughthelinelitothetankfl inwhichit is cooled to a temperature below its boiling pointunder atmospheric presnre, preferably cooled to a temperature I downtowards 78 C.

or methyl chloride is delivered to ,andthestinerflisputintooperaready,the tank member hand end of the reactor tank I. A

proximate saturation is r'eached the catalyst is delivered through thefilter ll and the cooler 02, which brings its temperature down close to"l8 C. and is stored in the tank 40 from which it is drawn to thecatalyst supply pipe II and its associated spray heads.

when the supply of cold oleflnic mixture is pipe I2 to a level whichbrings the surface layer of the liquidapproximately inch above the topof the barrier l. Simultaneously, the middle portion of the tank I isfilled with good-sized pieces of solid carbon dioxide and thecirculating propeller I is put into operation. When the reactor I isfilled to the proper level with the mixture of solid carbon dioxide andoleiinic reactants and is in rapid circulation across the top of thebarrier 3,

the catalyst flow is started through the spray heads or fine orifices(0.025" in diameteror less) on the pipe I I and the stream of dissolvedcatalyst is applied above or beneath the rapidly flowing, turbulentsurface of the reacting mixture above the barrier 3. The polymerizationbegins promptly and is continued in the free space at the right portionof the solid carbon dioxlde used to cool the reaction mixture dissolvesin the olefinic material, and is present in the reaction mixture at thetime of the polymerization. The polymerization reaction is exothermicand the heat llberated is in part used to raise the temperature of theoleilnic mixture, and in part to volatilize the dissolved carbondioxide. The volatilization of carbon dioxide occurs at the site of thepolymerization reaction, and accordingly the gasifled carbon dioxide isoccluded in the solid polymer formed, yielding a solid polymer,permeated with small bubbles of gaseous carbon dioxide. The presence ofthese gas bubbles causes the polymer to float upon the surface of thereaction mixture, leaving the unpolymerized residue free to returnthrough the suction duct I to the circulating well 5 and back throughthe solid carbon dioxide in the center portion of the tank where it iscooled for a returnover the top of the barrier 3.

As the solid polymer is produced it is skimmed of! by a workman, drainedwith pressure if desired, and thrown through the door I shown in Fig.-into the circulating warm water in the duct II. The warm water promptlyvolatilizes out any residual traces of unpolymerized reactants andpromptly quenches and destroys the aluminum chloride catalyst. The flowof water in the trough l0 carries the polymer to the collecting well I 8where it is separated from the flowing water by the strainer I0. The wetpolymer is collected from the well I0 by another operator and thrown outonto a draining platform where excess water is drained off. It is thentaken to the open roll mill shown in Fig. 5 for further processing,either simply drying, or drying and compounding with auxiliary reactantmaterial.

' The polymer as so produced is found to have a molecular weight withinthe range of about 20,000 to about 125,000 as determined by Staudingerpresented in "Die Hochmolecularen Organischen Verbindungen published byStaudinger at Berlin in 1932, the method being particularly well shownon page 56. The polymer likewise shows an iodine number as determined bythe Wills method of from 0.1 to 40 or 50. The polymer as obtained isreadily soluble in hydrocarbon solvents but because of its highmolecular weight, shows a very powerful thickening action in solutionand in the solid form shows the property of cold flow, being r isreactive with I is charged through the 6 an extremelyviscousliquid. Thepolymer sulfur and other substances in a curing reaction which destroysthe property of cold flow and develops an elastic limit, a highelongation and a good tensile strength. The polymers show tensilestrengths when cured ranging from 1,000 lbs. per square inch to 4,500

inellect lbs. per square inch and elongations at-break ranging from 500%to 1,200% depending upon the absence, or, presence and amount of variouscompounding agents. The polymer is conveniently cured with sulfur in thepresence of a sulfurization aid such as tetra methyl thiuram disulfldeand its analogous compounds. The polymer is also reactlve with paraquinone dioxime in an analogous curing reaction, and reactive withvarious of the analogous and homologous compounds.

For use the polymeris desirably compounded with carbon black, zincoxide, stearic acid and the curing agent, a suitable compounding recipebeing the following:

' Parts Copolymer Carbon black 50 Zinc oxide- 5 Stearic acid 3 Tetramethyl thiuram disulflde 1 This recipe is conveniently prepared bymilling the fresh polymer on the open roll mill until it is somewhatwarmed up andplasticize'd, then adding the compounding" agents in smallportions, cutting the sheet of polymer back and forth .across the faceof the millluntil the polymer is well incorporated. The compoundedpolymer may then be placed in moulds and cured by the application ofheat at temperatures ranging from C. to 200 C. for time intervalsranging from 180 minutes to 1 minute, depending upon the temperature andthe choice of curing agent.

Alternatively, the embodiment of Fig. 8 may be utilized, this being asimpler construction including a wooden tank member IN, a tray I02carrying solid carbon dioxide, a circulating propeller I03 on a shaftthe under side I02, a slanting far end I020 of the tray I02 and thebottom end of the tank IIII. In the operation of this embodiment thetray I02 is filled with solid carbon dioxide and the mixed reactantsprepared by equipment as shown in Fig. '7 are delivered to the tank IOIthrough a delivery pipe I I2. when the tank is full and the stream ofwater as in Fig. '5. The resulting polymer is closely similar in allrespects to the polymer produced by the first described embodiment.

. Thus the process of the present invention polymerizes an oleflnicmixture in the presence of a volatilizable refrigerant under conditionswhich cause the solid polymer to occlude substantial portions of thevolatilized refrigerant, thereby causing it to float freely uponthesurface of the reaction mixture from which it is readily skimmed off bya workman for further processing. In addition, the device of theinvention provides a simple tank member for the low temperature :5"polymerization of oleflnic mixtures in which sub- I0l working in acirculating duct formed of the partition I05 in conjunction with

